Involute checker



Dec. 30, 1941- J. J. OSPLACK INVOLUTE CHECKER Filed Aug. 2, 1940 2Sheets-Sheet l BY UAW W ATTORNEYS INVOLUTE CHECKER Filed Aug. 2, 1940 2Sheets-Sheet 2 INVENTOR 19 ATTORNEYS iaienied Dec. 39, 1941 INVOLUTECHECKER Joseph J. Osplack, Detroit, Mich asslgnor to Vlnco Corporation,Detroit, Mich, a corporation of Michigan Application August 2, 1940,Serial No. 349,587

12 Claims.

This invention relates to an involute checker for checking the accuracyof tooth profiles on involute gears, and particularly to an improvedmachine of this nature capable of checking gears of various sizes with ahigh degree of accuracy.

The object of the invention is to provide an improved-involute gearchecker of the type in which a support carrying an indicator point orstylus is so moved relative to a turning gear under test that the pathtraversed by the point relative to the gear is a true involute curve.The indicator point is held in contact with the profile of a tooth onthe gear, and departure of the tooth profile from a true involute curveis detected by a sensitive instrument responsive to movement of thepoint relative to its support.

This type of involute checker is based on the fundamental geometricalproperty of the involute curve, namely, that as the base circle of thegear rotates, a point on a tangent to the base circle which moves alongsuch tangent at the velocity of the base circle periphery follows thepath of a true involute profile of a tooth on the base circle. Checkersbased on this principle employ means for simultaneously turning the gearunder test and moving the indicator point along a tangent to the basecircle of the gear.

A particular object of the invention is the provision of an involutechecker of the type generally described embodying improved means forsimultaneously turning the gear under test and moving the indicatorpoint, which means permits checking of gears of a wide range of sizeswith a high and uniform degree of accuracy. Another object of theinvention is to provide an improved indicator point support andindicating instrument assembly which is readily adjustable to checkoppositely disposed tooth profiles and is at the same time highlyaccurate in its checking operation, Other objects include the provisionof an involute gear checker which is quickly and easily adjustable toaccommodate gears of different size without the necessity forcomplicated and time consuming re-setting operations.

The invention will be best understood from the following detaileddescription of an involute checker comprising a specific embodimentthereof. This device is illustrated in the accompanying drawings, inwhich: 7

Figure 1 is a front elevation of an involute checker embodying theinvention; and

Figure 2 is a side elevation of the checker as viewed from the right ofFigure 1, with the tail stock assembly removed.

The checker mechanism is mounted on a masslve unitary bed 3 andcomprises generally a head stock H, an indicator assembly P and a tailstock T. The bed 3 has spaced aligned horizontal ways 5 and 5 runninglengthwise thereof to which the head stock H and the tail stock T arerespectively clamped by suitable bolts 4. Gross adjustment of the tailstock T to accommodate gears of various axial length is obtained bymovement of the tail stock along the ways 5'.

A live spindle 6, journaled in ball bearings l, is carried in a sleeve 8slidably mounted in the tail stock T. Thesleeve and spindle are axiallyadjustable by means of a feed screw 9 engaging the nuts ID at the outerend of the sleeve 8 and driven by a hand crank l I. Rotation of thesleeve 8 in the tail stock is prevented by engagement of a key [2 in anelongated slot in the sleeve. The work-engaging end of the spindle 6comprises an accurately formed center point as shown. The head stock Hcarries a similar live spindle ll journaled in ball bearings 15 andformed to an accurate center point at its work-engaging end.

A circular dial plate I6 is suitably fixed to the spindle 14 adjacentits center point. A stationary pointer I8 is fixed to the head stock andoverlies the edge of the dial plate I6 which may be graduated in degreesso that the angle through which the gear is turned during a checkingoperation may be read.

A sectorial driving circle I! is removably fixed to the spindle It bysuitable means such as screws engaging a flange [8 on the spindle. Thedriving circle I! carries an upwardly extending counterweight 20 whichmaintains the circle sector in balance as it turns with the spindle.

The indicator assembly P is mounted to slide vertically on a way 2!fixed to a bracket 22 which is clamped to the bed 3 by suitable meanssuch as the bolt 23. A block 24 carries a slide 25 that engages the way2|. An anti-friction roller 26 is journaled between centers at the lowerend of the block 24, as shown in Figure l.

A plate 21 is slidably attached to the upper end of the block 24 and isadjustably movable transversely with the machine by a micrometer feedscrew, 28 (Figure 2). The plate 21 may be locked in any adjustedposition by a suitable clamp operated by the hand wheel 29. A horizontalway 30 extending lengthwise of the machine is fixed to the plate 21 andcarries a base 3| of the indicator support bar 32. The base 3| may bemoved to various positions lengthwise of the machine by sliding it inthe way 30, and may be locked in adjusted positions by a suitablelocking bolt 33.

The indicator support proper includes a split collar 34 surrounding andslidable vertically along thebarfl.Apinionlliournaledinanextensionofthecollarlland nsasinsarackilon lljournaled between suitable pivots I in a.

- the gear supporting spindles s and u. a m

housing 0 extending transversely of and eonnected'to the tubular casingll at'its outer end. The indicator point 44 is so shaped that itcontacts a tooth profile N at its outer end only, and is removably fixedin an opening in the inner end oi'therod ll by asetscrew ll. Adlaiindicator 40 of known construction is supported above the'indioatorpoint by a bracket 41 fined to the end of the casing IO, and theoperating rod ll of the dial indicator engages the rod ll adjacent theindicator point I. v

The point supporting rod ll extends through an opening in the outer wallof the pivot housing 43 and an upwardly extending weighted reversinglever 40 is pivotally secured to the outer endofthei-odasshown.Thepartsaresoproportloned that when the lever II is moved to its inwardposition as shown, its weighted end is substantially over the pivotshaft ll and the indicator point 44 is pressed downwardly by the weightof the supporting rod 40 so that the point 44 is maintained in contactwith an upwardly disposed tooth profile II, as shown in Figure 2. Whenit is desired tocheck a down-' wardly disposed tooth profile, the point44 is reversed so that its end will bear on such a profile, and thereversing lever ll is swung outward to the position shown in brokenlines in Figure 2. In this position, the weighted lever ll overbalancesthe rod II and point M and so biases the point upwardly and maintainsits end in contact with the downwardly disposed tooth profile beingchecked.

The indicator point and dial indicator supporting structure described pemits accurate checking without complicated re-setting operations. Thisresults from the location of the dial indicator operating rod ll betweenthe indicator point 44 and its pivot, and closer to the point than tothe pivot. This arrangement maintains a downward pressure on the pointpivot during checking of both upwardly and downwardly disposed toothprofiles, and thus obviates readjustment to compensate for play in thepivots. Also, false indications due to possible irregularities in thepivots are minimized because the lever arm between the pivot and thedial indicator operating rod III is long relative to that between theoperating rod and the end of the point M.

Improved mechanism is provided for simultaneously turning the gear beingchecked and moving the indicator point tangent to the base circle ofsuch gear at a velocity equal to the peripheral velocity of the basecircle. In the disclosed embodiment, this mechanism includes a carriage5| slidably supported in ways Land 53 extending transversely of the bed3. The line of movement of the bed is preferably horizontal and tangentto a circle centered on the axis of screw 54 operated by a hand wheel IIis provided forpropelling carriage ll along its ways. 7 A ver- 'ticallyextending post I is fixed to the carriage Bl adjacent one end thereof,and a horizontal friction drive bar "is pivotally secured at oneendtothepost. Thedrivebarlllssupported on a suitable roller such as theouter race of .a ballbearingllcarried byastubshaftll removably fixed inan opening in the head stock H. The bearing BI is so spaced relative tothe driving circle fl that the driving bar II is held in tightfrictional engagement with the periphery of the-driving circle. Withthis arrangement. horizontal-movement of the bar ll turns the circle I!without slippage between these parts,

and the pressure necessary to maintain this frictional engagementbetween the driving bar and the circle is transferred to the head stockK through the bearing-i8. Accordingly, no drag is imposed on thecarriage II by transmission of this pressure to the carriage ways It andII.

The friction driving bar I! may be moved to various vertically spacedpositions to engage driving circles of different diameter, and in thismanner, the relation between the angular velocity of the head spindle Itand thehorizontal velocity of the carriage ll may be altered. The changein position of the bar I! is made by moving its pivotal connection toone of the openings ll and ii in the post and moving the ball bearingstub shaft." to the corresponding opening 82 orilintheheadsiock H.

The indicator carriage ll carries a sine bar I pivotally connected tothe carriage at 65. The bar '4 is movable to various angular positionsin a vertical plane passing through the line of movement of the carriageII. The sine bar has a plane upper surface on which the indicatorassembly P is supported through engagement of the roller 20 with thissurface. The sine bar 64 may be disposed at various angles relative tothe horizontal line of movement of the carriage Ii by placing anaccurately dimensioned support such -as a Johannsen block I on a truehorizontal surface I of the canine ll beneath the free end of the-sinebar. A cylindrical button II is fixed to the undersurface of the sinebar 64 adjacent its free end to provide true and uniform engagement withblocks of various height. A handle may be provided at the free end ofthe sine bar for lifting it while various blocks are placed beneath itsfree end.

To check a gear tooth profile with the described checker, a drivingcircle ll having a radius preferably larger than that of the gear IIunder test is fixed to the spindle 8 and the gear is centered betweenthe points of the spindies 8 and I. A Johannsen block of the properheight is placed on the horizontal carriage surface I under the buttonit of the sine bar 64. The height of the block I used is so chosen as todispose the sine bar at a predetermined angle to the horizontal. Thisangle is such that upon horizontal movement of the carriage il, theindicator assembly P will be raised or lowered at a linear velocityequal to the peripheral velocity at which the base circle of the gearunder test is turned by such carriage movement. This angle may bereadily calculated since its tangent is equal to the base circlediameter of the gear under test divided by the diameter of the drivingcircle II. The block height required to produce this angle may bedetermined by multiplying the sine of the angle by the length of thehypotenuse formed by the with the proper block 08 in place, theindicator support is adjusted to place the end or the indicator point 44in contact with the upwardly disposed tooth profile II at the basecircle of the gear, this point of contact being in a horizontal planepassing through the center line or the spindles 8 and I4. The verticalposition or the indicator support collar 34 is adjusted until the pointsupport rod 40 is free to move in its tubular casing 39. The carriage inis then moved outward by the hand wheel 55, and this carriage movementboth turns the gear countel-clockwise as viewed in Figure 2 and liftsthe indicator point support vertically. During this movement, thedirection and magnitude of any departure of the tooth profile II from atrue involute curve is indicated by the dial indicator 4. When checkinga downwardly disposed tooth profile, such as the profile II on the samegear, the sine bar setting is not changed and the same-port,arollercan'ledbysaidsupportandengaging-saiddrivingbartoholdsaidbarinirlcdrivingcircle is employed. The point 44 and the lever 49 are reversed and thecarriage 5| is moved inwardly to rotate the gear clockwise as viewed inFigure 2 and to lower the indicator point.

By substituting larger diameter driving circles for the circle [1, largediameter gears may be checked without resort to excessive sine barangles. If, for example, the gear under test has a base circle diametergreater than that of the driving circle, the sine bar angle. wouldnecessarily be greater than 45 and the sensitivity and accuracy ofmovement 01 the indicator point support would be impaired. By changingto a larger diameter driving circle however, the sine bar angle may bekept within a 'range at which maximum sensitivity and accuracy ofmovement of the indicator point support is maintained.

I claim:

1. In an involute checker, in combination, a

rotatable gear supporting spindle having a fixedsubstantially horizontalaxis of rotation, an indicator point support movable along a substantialvertical line tangent to a circle centered on said axis, means forsimultaneously rotating said spindle and moving said indicator pointsupport comprising a carriage disposed below said indicator pointsupport and said spindle axis and movable horizontally along a linenormal to a vertical plane through said axis, means connected to saidcarriage for rotating said spindle upon movement of said carriage, a barpivotally secured adjacent one of its ends to said carriage and movableabout its pivot in a vertical plane parallel to the line of movement ofsaid carriage, a block removably disposed beneath said bar whereby saidbar is disposed at an angle to the line of movement of said carriage,and means on said indicator point support engaging said bar wherebyhorizontal movement 01 said carriage moves said indicator point supportvertically.

2. In an involute checker, in combination, a base, a verticallyextending support fixed to said base, a horizontal gear supportingspindle rotatably mounted on said support, a driving circle removablyfixed to said spindle adjacent said support, a carriage on said basebelow said spindle and movable along a line tangent to a circle centeredon the axis of rotation of said spindle, a horizontally extendingdriving bar pivotally connected to said carriage and engaging theperiphery of 'said driving circle adjacent said sup- 7 tional engagementwith the periphery or said driving circle, vertically spaced means onsaid carriageandsaidfixedsupportiorsupporting said driving bar and saidroller at different vertically spaced positions whereby said bar maycooperate with driving circles of different diameters, an indicatorpoint support carried by said base and movable vertically along a lineadjacent the axis of said spindle, a sine bar pivotally secured to saidcarriage and movable to various angular positions in a vertical planepassing through the line of movement of said carriage, a block removablydisposed between said sine bar and said carriage for holding said sinebar at a predetermined angle to the line of movement of said carriageand means on said indicator point support engaging said sine bar wherebyhorizontal movement of said carriage moves said indicator point supportvertically.

3. In an involute checker, in combination, a fixed support, a horizontalgear supporting spindle rotatably mounted on said support, a carriage onsaid support below said spindle movable along'a horizontal line, adriving connection between said carriage and said spindle for rotatingsaid spindle upon movement of said carriage, a sine bar pivotallysecured at one end to said carriage and movable in a vertical planethrough the line of movement of said carriage to positions at variousangles to the horizontal, a block removably disposed between saidcarriage and said bar for holding said bar at a predetermined angle tothe horizontal, and an indicator point support movable vertically alonga line adjacent the axis of said spindle and supported by said sine barwhereby horizontal movement of said carriage moves said indicator pointsupport vertically.

4. In an involute checker, in combination, a fixed support, a horizontalgear supporting spindle rotatably mounted on said support, a carriage onsaid support below said spindle movable along a horizontal line, adriving connection between said carriage and said spindle for rotatingsaid spindle upon movement of said carriage, a sine bar pivotallysecured at one end to said carriage and movable in a vertical planethrough the line of movement of said carriage to positions at variousangles to the horizontal, a cylindrical surface on said sine baradjacent its -free end having its axis parallel to the pivot axis orsaid bar, a block removably disposed between said carriage and saidcylindrical surface for supporting said bar at a predetermined angle tothe horizontal and an indicator point support movable vertically along aline adjacent the axis of said spindle and supported by said sine barwhereby horizontal movement of said carriage moves said indicator pointsupport vertically.

5. In an involute checker, in combination, a fixed support, a horizontalgear supporting spindle rotatably mounted on said support, a carriage onsaid support below said spindle movable along a horizontal line, adriving connection between said carriage and said spindle for rotatingsaid spindle upon movement of said carriage, a sine bar pivotallysecured at one end to said carriage and movable in a vertical planethrough the line of movement of said carriage to positions at variousangles to the horizontal, a cylindrical surface on said sine baradjacent its free end having its axis parallel to the pivot axis of saidbar, a block removably disposed between .said carriage and saidcylindrical surface for supporting said bar at a predetermined angle tothe horizontal, an indicator point support movable vertically along aline adjacent the axis of said spindle and a roller connected to saidindicator point support and engaging said sine bar whereby horizontalmovement oi said carriage moves said indicator point support vertically.

6. In an involute checker, in combination with means for rotating a gearto be checked about a fixed axis, a support and means for moving saidsupport along a vertically extending tangent to a circle centered onsaid axis, means carried by said support for checking a tooth on a gearcarried by said rotating means comprising an elongated element pivotallyconnected to said support and extending horizontally from its pivotalconnection toward said fixed axis for engagement at its free end with atooth on a gear being checked, a precision measuring instrument fixed tosaid support and a movable operating member on said instrument engagingsaid elongated element between its pivot and its free end and at a pointsubstantially closer to its free end than its pivot.

7. In an involute checker, in combination with a vertical movablesupport and means for simultaneously moving said support vertically androtating a gear to be checked about a fixed horizontal axis adjacentsaid support, means carried by said support for checking the shape of atooth profile on a gear rotated about said axis comprising an elongatedhorizontally extending member having a gear tooth engaging point at oneend thereof, a substantially horizontal pivot connecting said elongatedmember to said support at a point thereon remote from said tooth ensui gpoint, and'a dial indicator fixed to said support and having avertically movable operating rod engaging said elongated member close tosaid tooth engaging point and remote from said pivot.

8. In an lnvolute checker, in combination with a vertical movablesupport and means for simultaneously moving said support vertically androtating a gear to be checked about a fixed horizontal axis adjacentsaid support, means carried by said support for checking the shape oi atooth profile on a gear rotated about-said axis comprising an elongatedhorizontally extending member having a gear tooth engaging point at oneend thereof, a substantially horizontal pivot connecting said elongatedmember to said support adjacent the end thereof remote from said toothengaging point, a precision measuring instrument fixed to said supportand having a vertically movable operating element engaging saidelongated member, and a weight on said elongated member movablelongitudinally thereof from a position at which said tooth engagingpoint is biased upwardly to a position at which saidpoint is biaseddownwardly.

9. In an involute checker, in combination with a vertical movablesupport and means for simultaneously moving said support vertically andmoves said indicator rotatingageario-becheckedaboutafixedhorizontal axisadjacent said support, means carried'bysaidsupporttorcheckingtheshapeotatooth port and having a verticallymovable operating,

rod engaging said elongated member betweensaid pivot and said toothengaging point and adjacent said point, and a lever movably connected tosaid elongated member adjacent said pivot and having a weighted endmovable longitudinallyoi said member from a position at which said toothengaging point is biased upwardly to a pomtion at which said point isbiased downwardly.

10. An indicator point support for an involute checker comprising anelongated member having a gear tooth engaging point at one end thereofand a pivot spaced longitudinally oi said member from said point, aprecision measuring instrument fixed relative to said member and havinga movable operating element engaging said member adjacent said point andmovable upon movement of said member about said pivot and means forbiasing said member to turn in either direction about said pivot.

11. 'An indicator point support for an involute checker comprising anelongated member having a gear tooth engaging point at one end thereotand a pivot spaced longitudinally of said member from said point, aprecision measuring instrument fixed relative to said pivot and having amovable operating element engaging said member adjacent said point andmovable upon movement of said member about said pivot means forsupporting said instrument and said pivot in relatively fixed positionand a weight on said member movable horizontally relative to said pivotfor biasing said member to turn in either direction about said pivot.

12. In an involute checker, in combination, a base, a verticallyextending support fixed to said base, a horizontal gear supportingspindle rotatably mounted on said support, a driving circle removablyfixed to said spindle adjacent said support, a carriage on said basebelow said spindle and movable along a line tangent to a circle centeredon the axis oi rotation of said spindle, a horizontally extendingdriving bar pivotally connected to said carriage and engaging theperiphery oi said driving circle adjacent said support, a sine barpivotally secured to said carriage and movable to various angularpositions in a vertical plane passing through the line of movement ofsaid carriage, a block removably disposed between said sine bar and saidcarriage for holding said sine bar at a predetermined angle to the line0! movement of said carriage and means on said indicator point supportengaging said sine bar whereby horizontal movement or said carriagepointsupport vertically.

JOSEPH J. OSPLACK.

